High capacity storage facility using metal hydrogen batteries

Abstract

According to an embodiment of the present disclosure, a power storage facility is presented. The power storage facility includes: a housing containing hydrogen; a battery pack rigidly mounted within the housing, the battery pack including an array of metal hydrogen batteries; and a monitoring / control system coupled to each metal hydrogen cell in the array of individual metal hydrogen cells. In some embodiments, the power storage facility contains low pressure hydrogen.

Description

Technical Field

[0001] This disclosure claims priority to non-provisional patent application No. 17 / 947,978, filed on September 19, 2022, the entire contents of which are incorporated herein by reference. Background Art

[0002] In order for renewable energy sources such as wind and solar to compete with traditional fossil fuels, large-scale energy storage systems are needed to mitigate their inherent intermittency. To build large-scale energy storage, cost and long service life are the most important considerations. Currently, pumped hydro dominates the grid energy storage market because it is an inexpensive way to store large amounts of energy for a long period of time (about 50 years), but it is limited by the lack of suitable sites and environmental footprint. Other technologies such as compressed air and flywheel energy storage show some different advantages, but their relatively low efficiency and high cost should be significantly improved for grid energy storage. Rechargeable batteries provide an excellent opportunity to achieve large-scale energy storage systems with low cost, high capacity and high reliability. Summary of the invention

[0003] According to an embodiment of the present disclosure, a power storage facility is provided. The power storage facility includes: a housing containing hydrogen gas; a battery pack rigidly mounted within the housing, the battery pack including an array of metal hydride cells; and a monitoring / control system coupled to each metal hydride cell in the array of individual metal hydride cells. In some embodiments, the power storage facility contains low-pressure hydrogen gas.

[0004] A method of providing energy storage includes providing a housing for containing hydrogen gas; mounting a battery pack within the housing, the battery pack including an array of metal hydride cells; and monitoring the battery pack using a monitoring / control system coupled to each metal hydride cell in the array of individual metal hydride cells.

[0005] Other embodiments are considered and explained below. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] Some features of various embodiments of the present technology are described in detail in the appended claims. The features and advantages of the present invention will be better understood by referring to the following detailed description and its accompanying drawings, which set forth illustrative embodiments utilizing the principles of the present disclosure, wherein:

[0007] Figure 1A , Figure 1B , Figure 1C and Figure 1D Various sizes of facilities for storing energy are shown, according to some embodiments.

[0008] Figure 2A and Figure 2B A schematic diagram of a metal hydride cell that may be used in the facility shown in FIG. 1 is depicted.

[0009] Figure 3 The battery array shown in FIG. 2 is shown to form a Figure 1A , Figure 1B , Figure 1C and Figure 1D The battery pack shown.

[0010] Figure 4 An example of an energy storage facility is shown in accordance with some embodiments.

[0011] Figure 5 The graph shows the change of hydrogen pressure cycle curve over time at different pressure settings in a pressure vessel according to some embodiments.

[0012] Fig. 6A and Figure 6B A comparison of battery performance over different pressure ranges is shown according to some embodiments.

[0013] Fig. 7A and Figure 7B The performance of a 5-vessel shared pressure vessel (SPV) over the range of 50 to 150 psi hydrogen is shown as a function of cycle number, according to some embodiments. DETAILED DESCRIPTION

[0014] In the following description, certain specific details are set forth to provide a complete understanding of the various embodiments of the present disclosure. However, those skilled in the art will appreciate that the present disclosure may be implemented without these details. In addition, although various embodiments of the present disclosure are disclosed herein, many adjustments and modifications may be made within the scope of the present disclosure according to the general knowledge of those skilled in the art. Such modifications include replacing any aspect of the present disclosure with a known equivalent so as to achieve the same result in substantially the same manner.

[0015] Unless the context requires otherwise, throughout this specification and claims, the word "include" and variations thereof (such as "including" and "comprising") are to be interpreted in an open, inclusive sense, i.e., "including, but not limited to." Throughout this specification, the recitation of numerical ranges is intended to serve as a convenient notation that each individual value falling within the range is individually referred to, including the values ​​defining the range, and each individual value is incorporated into the specification as if it were individually recited herein. In addition, the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise.

[0016] Throughout the specification, references to "one embodiment" or "an embodiment" mean that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present disclosure. Thus, the phrases "in one embodiment" or "in an embodiment" appearing in various places throughout this specification are not necessarily all referring to the same embodiment, but may do so in some cases. Furthermore, particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.

[0017] Embodiments of the present disclosure describe an electrode of a metal hydrogen battery formed by one or more porous layers. Each porous layer includes a porous substrate and a catalyst layer covering the porous substrate, the catalyst layer including a transition metal. At least one of the one or more porous layers includes a surface having a feature that promotes hydrogen transport. In some embodiments, the anode electrode includes a first porous layer having a first surface; and a second porous layer having a second surface adjacent to the first porous layer, wherein the first surface of the first porous layer and the second surface of the second porous layer form a hydrogen transport channel.

[0018] Figure 1A A storage facility 100 is shown according to some embodiments of the present disclosure. Figure 1A As shown, storage facility 100 includes housing 104 that encloses battery pack 106. Housing 104 may be a large spherical shell that is large enough to enclose battery pack 106. Battery pack 106 occupies a portion of interior space 102, which is also filled with hydrogen gas. In some embodiments, battery pack 106 may be located in a separate housing that is external to interior space 102 and coupled to interior space 102. In some embodiments, entrance 108 allows access to the interior of storage facility 100, which may be important for maintenance, assembly, or other activities. Figure 1A As further shown, the housing 104 of the storage facility 100 can be at least partially located underground, although the entire facility can be located completely above ground or completely underground.

[0019] Figure 1A , Figure 1B , Figure 1C and Figure 1D The embodiment of the storage facility 100 shown in the embodiment includes a shell 104 that is spherical in shape. However, other shapes, such as rectangular or cylindrical, may also be used. The shell 104 can be formed of concrete or other suitable structural materials. In some embodiments, the shell 104 can be formed of a material configured to accommodate hydrogen. In some embodiments, the shell 104 can include a lining formed within the shell 104 or around the outer surface of the shell 104 to help contain the hydrogen in the interior space 102.

[0020] Figure 1A , Figure 1B , Figure 1C and Figure 1D The relative size of the storage facility 100 is shown compared to the power storage capacity of the facility 100. Figure 1A An example of a 2 GWh facility is shown, which in some embodiments may include an outer diameter of 81 m for the enclosure 104. In these embodiments, the size of the enclosure 104 depends on the physical size of the battery pack 106 and the capacity and pressure of the hydrogen storage capacity required for the operation of the battery pack 106. In some embodiments, the size of the battery pack 106 may also include maintenance access for servicing the battery pack 106. Figure 1B A 200MWh storage facility 100 is shown, as Figure 1A , the storage facility 100 may have a housing 104 having an outer diameter of 37 m. Figure 1C A 20 MWh storage facility 100 is shown which may have a housing 104 with an outer diameter of 17.5 m. Figure 1D A 2 MWh storage facility 100 is shown, which may have an outer diameter of 8 m for the housing 104. These specific examples are for illustration purposes only, and as described above, are limited only by the size of the battery pack 106 and the amount and pressure of hydrogen stored to operate the battery pack 106. The size and structure of the storage facility may be calculated so that the operating hydrogen pressure does not exceed the maximum allowable design pressure, such as a low pressure of 500 psi or less, 200 psi or less, or 100 psi or less.

[0021] like Figure 1A , Figure 1B , Figure 1C and Figure 1D As shown, the battery pack 106 can be formed of an array of individual batteries. These individual batteries can be arranged in an array and coupled in parallel and / or series configurations depending on the output voltage and current requirements of the storage facility 100. The total storage capacity is determined by the number of individual batteries included in the battery pack 106.

[0022] Figure 2A and Figure 2B Schematic diagram of a metal hydride battery 200 that can be used in the battery pack 106 is shown. Figure 2AAs shown, the metal hydrogen battery 200 includes an electrode stack assembly 230, which includes stacked electrodes separated by a separator 206. The electrode stack assembly 230 includes cathode electrodes 202 and anode electrodes 204 stacked alternately. The cathode electrode 202 and the anode electrode 204 are separated by a separator 206 disposed therebetween. The separator 206 can be immersed in an electrolyte 208. In some embodiments, in addition to electrically isolating the cathode electrode 202 from the anode electrode 204, the separator 206 also provides a reservoir of the electrolyte 208, which buffers the drying out or flooding of the electrodes during operation of the battery 200.

[0023] like Figure 2A As shown, the electrode stack assembly 230 can be housed in a container 209. As shown, the electrolyte 208 is disposed in the container 209 so that the stack 230 is immersed in the electrolyte 208. The cathode electrode 202, the anode electrode 204, and the separator 206 are porous to receive the electrolyte 208 and allow ions in the electrolyte 208 to be transmitted between the cathode electrode 202 and the anode electrode 204. In some embodiments, as long as the cathode electrode 202 and the anode electrode 204 can be electrically insulated from each other and sufficient electrolyte 208 can be received in the electrode stack 230, the separator 206 can be omitted. For example, the space occupied by the separator 206 can be filled with the electrolyte 208.

[0024] Figure 2A The metal hydrogen battery 200 shown in may also include one or more filling tubes 222 and 226 configured to introduce an electrolyte or gas (e.g., hydrogen) into the container 209. In some embodiments, the container 209 may be any material that holds the electrolyte 208 but is permeable to the flow of hydrogen. For example, the container 209 may be a plastic bag or a plastic container in which the electrode stack 230 is placed. The filling tubes 222 and 226 may include one or more valves (not shown) to control the flow of hydrogen into and out of the housing of the container 209, or the filling tubes 222 and 226 may be sealed by other means after the electrolyte 208 and possible hydrogen are filled into the container 209. In some embodiments, the valve may be formed of a material that is permeable to hydrogen and impermeable to liquids. In some embodiments, the container 209 may include a plurality of electrode stacks 230.

[0025] like Figure 2A As shown and described above, the electrode stack assembly 230 includes multiple stacked layers of alternating cathode electrodes 202 and anode electrodes 204 separated by separators 206. Although the electrodes in the electrode stack assembly 230 can be coupled in parallel or in series, in Figure 2AIn the example of battery 200 shown, the electrodes are coupled in parallel. Specifically, each of cathode electrodes 202 is coupled to conductor 218, and each of anode electrodes 204 is coupled to conductor 216. Figure 2A Fill tubes 222 and 226 are shown located at the ends, but fill tubes 222 and 226 may alternatively be placed anywhere on container 202. In some embodiments, battery 200 may include only one of fill tubes 222 and 226.

[0026] like Figure 2A As further shown in FIG. 2 , conductor 216 coupled to anode electrode 204 is electrically coupled to feed-through terminal 220, which may present one terminal of battery 200. Terminal 220 may include a feed-through to allow terminal 220 to extend outside of container 209. Similarly, conductor 218 coupled to cathode electrode 202 may be coupled to feed-through terminal 224, which represents the opposite (positive) terminal of battery 200. Terminal 224 also passes through an insulating feed-through to allow terminal 224 to extend outside of container 209 because terminal 224 is coupled to cathode electrode 204.

[0027] like Figure 2A As shown in , the electrode stack 204 can be fixed in the frame 232. Figure 2A , the electrode stack assembly 230 can be organized such that the anode electrode 204 is on both sides near the frame 232 so as to isolate the cathode electrode 202 from the frame 232. In some embodiments, a separator 206 can be included near the frame 232 for further isolation, particularly if the electrode stack assembly 230 is arranged so that the cathode electrode 202 is adjacent to the frame 232 rather than the anode electrode 204.

[0028] As described above, the electrode stack 230 includes alternating layers of cathode electrodes 202 and anode electrodes 204 separated by separators 206. The electrode stack assembly 230 is located in a container 209 and contains an electrolyte 208, wherein ions in the electrolyte 208 can be transferred between the cathode electrode 202 and the anode electrode 204. The separator 206 can be a porous insulator. In some embodiments, the electrolyte 208 is an alkaline (pH greater than 7) aqueous electrolyte.

[0029] For example, examples of the battery 200 shown in FIG. 2 are discussed in greater detail in U.S. patent application 17 / 687,527, filed on March 4, 2022 (titled “Electrode Stack Assembly for a Metal Hydrogen Battery”); U.S. patent application 63 / 347,908, filed on June 1, 2022 (titled “Electrode Stack Assembly for a Metal Hydrogen Battery”); and U.S. patent application 17 / 847,591, filed on June 23, 2022 (titled “Electrode for Metal Hydrogen Battery and Method for Manufacturing Same”), each of which is incorporated herein by reference in its entirety.

[0030] like Figure 2A As further shown in FIG. 2 , the battery 200 can be coupled to a monitoring / control system 232. The battery 200 can include a sensor 228 that provides a signal to the monitoring / control system 232, such as related to the state of the electrolyte 208 in the electrode stack 230 of the battery 200. In addition, the electrodes 220 and 224 can also be monitored so that the monitoring / control system 232 can determine performance parameters (such as the state of charge and other parameters). Thus, the monitoring / control system 232 can determine the efficiency of the battery 200 and indicate whether the battery 200 is operating within acceptable parameters or whether the battery 200 is malfunctioning.

[0031] In some embodiments, Figure 2B As shown, the battery 200 can include multiple electrode stacks 230 in each housing 209. Such configurations are further described in U.S. patent application Ser. No. 17 / 898,098, filed Aug. 29, 2022, entitled “Nickel-Hydrogen Battery Configurations for Grid-Scale Energy Storage,” the entire contents of which are incorporated herein by reference.

[0032] Figure 3An example of a battery pack 106 formed of batteries 200-1,1 to 200-M,N is shown. As shown, the battery pack 106 includes M rows of N series-coupled batteries 200. Each of the M rows is coupled in parallel between facility terminals 302 and 304. Thus, the batteries 200-1,1 to 200-1,N are coupled in series, and the row is coupled in parallel with the series-coupled batteries 200-m,1 to 200-m,N. Each of the batteries 200-1,1 to 200-M,N can be the battery 200 described in FIG. 2.

[0033] like Figure 3 As further shown in FIG. 1 , the monitoring / control system 232 is coupled to monitor each of the batteries 200-1,1 through 200-M,N. The monitoring / control system 232 may also monitor the facility terminals 302 and 304 to monitor the performance of the battery pack 106. As described above, the monitoring / control system 232 may monitor each of the batteries 200-1,1 and 200-M,N and may determine whether one or more of them is faulty and requires maintenance.

[0034] Figure 4 It shows that Figure 1A , Figure 1B , Figure 1C and Figure 1D An embodiment of the facility 100 is shown. Figure 4 As shown, the housing 104 can be a rigid outer sphere. As described above, the housing 104 is configured to contain hydrogen at an operating pressure and temperature in the interior space 102. In some embodiments, a liner 402 is formed on the inner surface or outer surface of the housing 104, and the liner can be formed of a hydrogen-containing material. The liner 402 can be formed, for example, of a plastic material such as polyethylene. In some embodiments, the liner 402 can be a metal or a metal alloy, such as stainless steel.

[0035] like Figure 4 As further shown, the battery pack 106 includes a bracket 406 on which the batteries 200-1,1 to 200-M,N are mounted. The bracket 406 can be any structure that can securely hold the batteries 200-1,1 to 200-M,N. In some embodiments, the bracket 406 can be arranged to allow maintenance. Figure 4 As further shown, the portal 108 may include a control room 404 , which may include the monitoring / control system 232 .

[0036] The cell 200 as described above can be operated at low hydrogen pressure. Figure 5 The hydrogen pressure cycle curves under different pressure settings are shown. Specifically, Figure 5A voltage curve 502 of a battery versus time is shown, as is a pressure curve 504 of the battery versus time, according to some embodiments. Region 506 is expanded to show that the battery is operating at a much lower pressure (e.g., 20 to 80 psi) rather than the 200 to 1000 psi otherwise shown. Figure 5 As shown, in region 506, there is little difference between the operation of the battery at high pressure and the operation of the battery at low pressure.

[0037] Fig. 6A and Figure 6B Coulombic efficiency (CE), voltage efficiency (VE), and energy efficiency (EE) of cells according to some embodiments over several ranges of hydrogen pressures are shown. Fig. 6A shows a C / 4 efficiency, while Figure 6B The C / 2 efficiency is shown. Specifically, Fig. 6A and Figure 6B The efficiencies are shown for pressure range 602 of 200 to 950 psi, pressure range 604 of 58 to 63 psi, and pressure range 606 of 25 to 30 psi. Fig. 6A and Figure 6B It can be seen that the efficiency of the battery in the low pressure range 604 is substantially the same as the efficiency in the high pressure range 602. These efficiencies are also shown in Table 1. As shown, the efficiency drops slightly in the lowest pressure range 606. Therefore, operation of the battery in the low pressure range 604 or even the lowest pressure range 606 can be used.

[0038] Fig. 7A and Figure 7B Long term cycling performance of a five (5) vessel shared pressure vessel (SPV) at hydrogen pressures ranging from 50 to 150 psi is shown. The SPV may be used in embodiments of the present disclosure. Fig. 7A The CE and EE efficiencies of the SPV over 250 cycles are shown and exhibit consistent operation. Figure 7B The charge and discharge energies over 250 cycles are shown and again demonstrate consistent operation.

[0039] Table I

[0040]

[0041] As indicated above, one or more electrode stacks 230 may be arranged within facility 100 and operated at low pressure and at low hydrogen pressure (e.g., less than 500 psi, less than 200 psi, less than 100 psi, or less than 50 psi). This greatly reduces the high capital cost of the pressure vessel formed by housing 104. As indicated above, container 209 may be any material that allows hydrogen transport and prevents electrolyte flow. The low hydrogen pressure within facility 100 allows for the practical construction of large-scale (2 MWh or larger) storage facilities, such as Figures 1A to 1D Thus, the facility 100 may be constructed using conventional techniques using steel and prestressed concrete composites. Thus, such a facility 100 may meet applicable building codes and standards at the location where the facility 100 is constructed.

[0042] Aspects of the present disclosure describe an electricity storage facility. Selection of the many aspects of the present disclosure may include the following aspects:

[0043] Aspect 1: An electricity storage facility comprises: a housing containing hydrogen gas; a battery pack rigidly mounted within the housing, the battery pack comprising an array of metal hydride cells; and a monitoring / control system coupled to each metal hydride cell in the array of individual metal hydride cells.

[0044] Aspect 2: The power storage facility according to aspect 1, wherein each metal hydride battery comprises: a container; and an electrode stack within the container, the electrode stack comprising a stacked cathode electrode and an anode electrode separated by a separator.

[0045] Aspect 3: The power storage facility according to aspects 1 to 2, further comprising: a plurality of electrode stacks within the container, each of the plurality of electrode stacks comprising a stacked cathode electrode and an anode electrode separated by a separator.

[0046] Aspect 4: The power storage facility according to aspects 1 to 3, wherein the electrode stack is immersed in an electrolyte, and the container accommodates the electrolyte and is permeable to the hydrogen gas.

[0047] Aspect 5: The power storage facility according to aspects 1 to 4, wherein the battery pack operates at a low hydrogen pressure of the hydrogen gas.

[0048] Aspect 6: The power storage facility according to aspects 1 to 5, wherein the low hydrogen pressure is less than 500 psi.

[0049] Aspect 7: The power storage facility according to aspects 1 to 6, wherein the low hydrogen pressure is less than 200 psi.

[0050] Aspect 8: The power storage facility according to aspects 1 to 7, wherein the low hydrogen pressure is less than 100 psi.

[0051] Aspect 9: The power storage facility according to aspects 1 to 8, wherein the housing includes a lining for containing hydrogen.

[0052] Aspect 10: The power storage facility according to aspects 1 to 9, wherein the shell is composed of steel and stressed concrete.

[0053] Aspect 11: The power storage facility according to aspects 1 to 10, wherein the battery pack provides energy storage greater than 2 GWh.

[0054] Aspect 12: The power storage facility according to aspects 1 to 11, wherein the monitor / controller is configured to monitor and control the operation of each metal hydride battery.

[0055] Aspect 13: A method of providing energy storage, comprising: providing a housing for containing hydrogen gas; installing a battery pack within the housing, the battery pack including an array of metal hydride cells; and monitoring the battery pack using a monitoring / control system coupled to each metal hydride cell in the array of individual metal hydride cells.

[0056] Aspect 14: The method according to aspect 13, wherein each metal hydride battery comprises: a container; and an electrode stack within the container, the electrode stack comprising a stacked cathode electrode and an anode electrode separated by a separator.

[0057] Aspect 15: The method according to aspects 13 to 14, further comprising: a plurality of electrode stacks within the container, each of the plurality of electrode stacks comprising a stacked cathode electrode and an anode electrode separated by a separator.

[0058] Aspect 16: The method according to aspects 13 to 15, wherein the container contains an electrolyte and is permeable to the hydrogen gas.

[0059] Aspect 17: The method according to aspects 13 to 16 further includes: operating the battery pack under low hydrogen pressure.

[0060] Aspect 18: The method according to aspects 13 to 17, wherein the low hydrogen pressure is less than 500 psi.

[0061] Aspect 19: The method according to aspects 13 to 18, wherein the low hydrogen pressure is less than 200 psi.

[0062] Aspect 20: The method according to aspects 13 to 19, wherein the low hydrogen pressure is less than 100 psi.

[0063] Aspect 21: The method according to aspects 13 to 20 further includes: providing a lining layer containing hydrogen to the outer shell.

[0064] Aspect 22: The method according to aspects 13 to 21, wherein: providing the shell includes constructing the shell with steel and stressed concrete.

[0065] Aspect 23: A method according to aspects 13 to 22, wherein the battery pack provides energy storage greater than 2 GWh.

[0066] The above description of the present disclosure has been provided for the purpose of illustration and description. It is not intended to be exhaustive or to limit the precise form of the present disclosure. The breadth and scope of the present disclosure should not be limited by any of the above exemplary embodiments. Many modifications and variations will be obvious to those of ordinary skill in the art. These modifications and variations include any relevant combination of the disclosed features. The selection and description of the embodiments are to best explain the principles of the present disclosure and its practical application, so that other technical personnel in the art can understand the various embodiments of the present disclosure and the various modifications suitable for the intended specific use. It is intended that the scope of the present disclosure is defined by the appended claims and their equivalents.

Claims

1. An electric power storage facility comprising: a housing containing hydrogen gas; a battery pack rigidly mounted within the housing, the battery pack comprising an array of metal hydride cells; as well as A monitoring / control system is coupled to each metal hydride cell in the array of individual metal hydride cells.

2. The power storage facility according to claim 1, wherein: Each metal hydride battery includes: Container; and An electrode stack is provided within the container, the electrode stack comprising a stacked cathode electrode and an anode electrode separated by a separator.

3. The power storage facility according to claim 2, further comprising: A plurality of electrode stacks are provided within the container, each of the plurality of electrode stacks comprising a stacked cathode electrode and an anode electrode separated by a separator.

4. The power storage facility according to claim 2, wherein: The electrode stack is immersed with an electrolyte, and the container contains the electrolyte and is permeable to the hydrogen gas.

5. The power storage facility according to claim 1, wherein: The battery pack operates at a low hydrogen pressure of the hydrogen gas.

6. The power storage facility according to claim 5, wherein: The low hydrogen pressure is less than 500 psi.

7. The power storage facility according to claim 5, wherein: The low hydrogen pressure is less than 200 psi.

8. The power storage facility according to claim 5, wherein: The low hydrogen pressure is less than 100 psi.

9. The power storage facility according to claim 1, wherein: The housing includes a liner that contains hydrogen gas.

10. The power storage facility according to claim 1, wherein: The shell is constructed of steel and stressed concrete.

11. The power storage facility according to claim 1, wherein: The battery pack provides greater than 2GWh of energy storage.

12. The power storage facility according to claim 1, wherein: The monitor / controller is configured to monitor and control the operation of each metal hydride cell.

13. A method for providing energy storage, comprising: providing an enclosure for containing the hydrogen gas; installing a battery pack in the housing, the battery pack comprising an array of metal hydride cells; as well as The battery pack is monitored using a monitoring / control system coupled to each metal hydride cell in an array of individual metal hydride cells.

14. The method according to claim 13, wherein: Each metal hydride battery includes: Container; and An electrode stack is provided within the container, the electrode stack comprising a stacked cathode electrode and an anode electrode separated by a separator.

15. The method according to claim 14, further comprising: A plurality of electrode stacks are provided within the container, each of the plurality of electrode stacks comprising a stacked cathode electrode and an anode electrode separated by a separator.

16. The method according to claim 15, wherein: The container accommodates an electrolyte and is permeable to the hydrogen gas.

17. The method according to claim 13, further comprising: The battery pack is operated at low hydrogen pressure.

18. The method according to claim 17, wherein: The low hydrogen pressure is less than 500 psi.

19. The method according to claim 17, wherein: The low hydrogen pressure is less than 200 psi.

20. The method according to claim 17, wherein: The low hydrogen pressure is less than 100 psi.

21. The method of claim 13, further comprising: The housing is provided with a lining containing hydrogen gas.

22. The method according to claim 13, wherein: Providing the shell includes constructing the shell from steel and stressed concrete.

23. The method according to claim 13, wherein: The battery pack provides greater than 2GWh of energy storage.

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